Process of making polyurethane fiber or film

ABSTRACT

This invention provides processes for preparing fiber or film comprising a polyurethane and layers delaminated from a lamellar clay, said layers being dispersed in said polyurethane. Fiber and film produced by the processes of the present invention exhibit reduced tack and an increased ability to affix at least one dye.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of Ser. No. 09/202,577, filed Dec. 17,1998, now U.S. Pat. No. 6,203,901 which was filed under 35 U.S.C. 371from International Application No. PCT/US97/10887 filed Jun. 23, 1997which claims priority benefit of Provisional Application No. 60/020,298filed Jun. 24, 1996.

FIELD OF THE INVENTION

This invention relates to polyurethane fibers and films. Moreparticularly, the invention concerns an improvement in such fibers andfilms wherein a lamellar clay is incorporated into the polyurethane.Results of the improvement are significantly decreased tack in suchfibers and films and a significantly increased ability to provide dyedfibers and film.

TECHNICAL BACKGROUND

Elastomeric fibers, such as those made from polyurethane, are suitablefor fibers and fabrics due to their outstanding stretch and recoveryproperties. However certain polyurethane filaments are very tackycompared to conventional textile filaments, such as those melt-spun fromnylon or polyester polymers. These polyurethane filaments tend to stickto each other, especially when wound on a pirn, bobbin, cake or othersuch yarn package. Tackiness can manifest itself in fused filamentsegments and high yarn-to-yarn friction. Also, on being unwound from ayarn package, the polyurethane filaments can experience excessivetension and large, rapid transient increases in tension, which in turnlead to many broken filaments during operations such as covering,knitting, weaving and the like. Further, because the polyurethanefilaments are subjected to higher compressive forces when they arelocated in the inner layers of a wound up yarn package, as compared tothe compressive forces on the filaments in the outer layers, averagetension and numbers of tension transients can change significantly asthe filaments are unwound from the yarn package. Such tension variationsproduce nonuniformities in fabrics made with fibers produced frompolyurethane supplied from such packages. Tack between fibers is knownto increase with aging on the package form. In addition to time, higherthan ambient storage temperatures can accelerate the increase in tackthus limiting the ability to remove fiber from the package in knittingor other fabric forming processes. Thus agents that slow this increasingtack are desired for extended usefulness of fiber stored on the package.Polyurethane films can also exhibit similar problems as the result oftackiness.

To reduce tackiness certain additives have been introduced intopolyurethane fiber, such as spandex. These additives include silicon oiland metal stearates. In addition, various finishes have been suggestedfor lubricating the surfaces of the fiber and thus reducing thetackiness of spandex. However, further improvements are desired.

In addition to the tack problem, certain polyurethane filaments are noteasily dyeable as compared to conventional textile filaments, such asthose melt-spun from nylon or polyester. Other polyurethane filamentsmay accept dye, but the dye tends to wash out readily. Spandex is oftencovered or blended with other fibers such as those made from polyamide,i.e. nylon, and polyester. However, when such fibers and fabrics arestretched, the undyed or slightly stained spandex shows through thecolored fiber covering. This is referred to as “grin through”. Inaddition, the spandex reflects visible light causing a glitter effect.Both “grin through” and glitter are objectionable in most dyed fabrics.Polyurethane film can also be difficult to dye.

An object of the present invention is to provide improved polyurethanefibers, and fabrics made therefrom, and films that possess reduced tackand processes for providing such fibers. Another object of the presentinvention is to provide improved polyurethane fibers, fabrics, and filmsthat permit enhanced dyeability and washfastness. A further object ofthe present invention is to provide processes which increase the abilityto provide dyed fiber and films. These improvements will permit moreefficient utilization of the fiber in yarn and fabric making operationsand the film in other applications, such as coatings, while retainingother desirable elastomeric properties.

SUMMARY OF THE INVENTION

The present invention provides a fiber, comprising: a wet- or dry-spunproduct which comprises a polyurethane and layers delaminated from alamellar clay, said layers being dispersed in said polyurethane.

The present invention also provides a process for preparing a fibercomprising a wet- or dry-spun product which comprises a polyurethane andlayers delaminated from a lamellar clay, said layers being dispersed insaid polyurethane, the process comprising the steps of:

(a) contacting a solution comprising a polyurethane and an aprotic polarsolvent with a lamellar clay, or with a dispersion of said lamellar clayin the aprotic polar solvent, to form a polyurethane/clay dispersion;

(b) agitating the polyurethane/clay dispersion sufficient to delaminateall or a portion of said layers from the lamellar clay and from eachother, and

(c) wet- or dry-spinning the polyurethane/clay dispersion to form afiber.

The present invention also provides a process for preparing a dyed fibercomprising a wet- or dry-spun product which comprises a polyurethane,layers delaminated from a lamellar clay, and a dye, said layers and saiddye being dispersed in said polyurethane, the process comprising thesteps of:

(a) contacting a clay dispersion comprising a lamellar clay and asolvent with a dye solution comprising an organic dye to form a firstdye/clay dispersion:

(b) recovering a dyed clay from the first dye/clay dispersion;

(c) contacting a solution comprising a polyurethane and an aprotic polarsolvent with a second dye/clay dispersion comprising the dyed clay andthe aprotic polar solvent to form a dye/clay/polyurethane dispersion;

(d) agitating the dye/clay/polyurethane dispersion sufficient todelaminate all or a portion of said layers from the lamellar clay andfrom each other; and

(e) wet- or dry-spinning the dye/clay/polyurethane dispersion to form adyed fiber.

The present invention further provides a film, comprising: a solutioncast product which comprises a polyurethane and layers delaminated froma lamellar clay, said layers being dispersed in said polyurethane.

The present invention also provides a process for preparing a film whichcomprises a polyurethane and layers delaminated from a lamellar clay,said layers being dispersed in said polyurethane, the process comprisingthe steps of:

(a) contacting a solution comprising a polyurethane and an aprotic polarsolvent with a lamellar clay, or with a dispersion of said lamellar clayin the aprotic polar solvent, to form a polyurethane/clay dispersion;

(b) agitating the polyurethane/clay dispersion sufficient to delaminateall or a portion of said layers from the lamellar clay and from eachother; and

(c) casting and drying the polyurethane/clay dispersion to form a film.

The present invention further provides a process for preparing a dyedfilm comprising a polyurethane, layers delaminated from a lamellar clay,and a dye, said layers and said dye being dispersed in saidpolyurethane, the process comprising the steps of contacting a claydispersion comprising a lamellar clay and a solvent with a dye solutioncomprising an organic dye to form a first dye/clay dispersion;recovering a dyed clay from the first dye/clay dispersion; contacting asolution comprising a polyurethane and an aprotic polar solvent with asecond dye/clay dispersion comprising the dyed clay and the aproticpolar solvent to form a dye/clay/polyurethane dispersion; agitating thedye/clay/polyurethane dispersion sufficient to delaminate all or aportion of said layers from the lamellar clay and from each other; andsolution casting and drying the dye/clay/polyurethane dispersion to forma dyed film.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graphical representation from Example 4 of peel force (J/m²)as a function of time for various polyurethane films having modifiedclay, unmodified clay or no clay dispersed therein showing film to filmadhesion growth.

FIG. 2 is a graphical representation of Example 5 showing tack growth ofa 15 denier spandex as a function of time for fiber at the core, middleand surface of a spool. One fiber containing 2% organic onium modifiedlamellar clay (dotted line with a square) was compared with a control,i.e. spandex having no clay, (solid line with triangle). Aging tookplace at 24° C.

DETAILED DESCRIPTION OF THE INVENTION

Polyurethane of the present invention includes polyurethane elastomers,segmented polyurethane, polyurethaneurea, and the like. Preferably thepolyurethane is a segmented polyurethane useful in the manufacture ofspandex. As used herein, the term “spandex” is a long chain syntheticfiber comprised of at least 85% by weight of a segmented polyurethane.The segmented polyurethane is composed of “soft segments” and “hardsegments”. The soft segments can be polyether-based portions of thepolymer chain, e.g., are derived from a poly(tetrarmethyleneether)glycol(PO4G). The hard segments refer to the portions of the polymer chainswhich are derived from the reaction of an organic diisocyanate, such asmethylene-bis-(4-phenylisocyanate) (MDI), with a diamine chain extender.

Polyethers suitable for use in making the glycol soft segment of thespandex polymer of the present invention include but are not limited tothose derived from tetramethylene glycol, 3-methyl-1,5-pentane diol,tetrahydrofuran (THF), 3-methyltetrahydrofuran (3-MeTHF), and the like,and copolymers thereof. PO4G usually has a number average molecularweight in the range of 1750 to 2250.

Copolyether glycols of this composition may be prepared according to thegeneral procedures of U.S. Pat. No. 5,000,899 and references therein.

Glycol-terminated polyesters which may be used in conjunction with thepresent invention include but are not limited to the reaction productsof ethylene glycol, tetramethylene glycol, and/or2,2dimethyl-1,3-propane diol and the like with diacids such as adipicacid, succinic acid, dodecanedioic acid, and the like. Copolymers arealso contemplated.

Also contemplated as soft segments for use in the present invention arepolyetheresters comprised of elements of the above polyethers andpolyesters, and diol-terminated polycationates such aspoly(pentane-1,5carbonate) diol and poly(hexane-1,6carbonate) diol, andthe like.

It is well-known in the art that completion of the formation of thepolyurethane may be accomplished with diamines which act as chainextenders, to form polyurethaneureas. Those that may be used with thepresent invention include ethylene diamine, 1,3-cyclohexane diamine(HMPD), 1,4cyclohexane diamine (HPPD), 1,3-propylene diamine (1,3-PDA),2-methylpentamethylene diamine (MPMD), 1,2-propylene diamine (1,2-PDA),1,2-diaminoethane (EDA) and the like, and mixtures thereof. Chainextension may also be accomplished with diols such as ethylene glycol,tetramethylene glycol, and so on. Chain extension can also be done withdiacids, such as adipic acid.

The chemical names of polyurethane may be abbreviated according to theircompositions. Monomers of the repeating units of the polymer areseparated by colons. For example, a polyurethaneurea made frompoly(tetramethyleneether)glycol (PO4G),methylene-bis(4-phenylisocyanate) (MDI) and a mixture of ethylenediamine (EDA) and 2-methyl-1,5-diaminopentane (MPMD) is abbreviatedPO4G:MDI:EDA/MPMD. Diamines separated by slashes are in a mixture.Parenthetic numbers immediately following the glycol and diamine mixturerespectively, refer to the number average molecular weight of the glycoland the molar ratio of the given diamines. Thus, for example, apolyurethaneurea of the present invention is abbreviated as:PO4G(1800):MDI:EDA/PDA(85/15). A preferred polyurethane of the presentinvention is PO4G(1800):MDI:EDA/MPMD(90/10).

The reactions used for preparing the polyurethane generally are carriedout in an inert solvent, such as dimethylacetamide (DMAc),dimethylformamide. N-methylpyrrolidone or the like.

“Lamellar clay” as used in the present invention is a layered clayhaving negative charges on its layers and exchangeable cations in theinterlayer regions Besides its cation-exchanging ability, the lamellarclay of the present invention further exhibits the property of beingcapable of incorporating water, alcohol or similar compounds into theinterlayers and expanding. Water and the other polar organic compoundsinteract with the lamellar clay. The polar organic compounds can bealcohol (primary alcohols like methanol, ethanol and the like andpolyhydric alcohols like ethylene glycol, glycerol and the like),ketones, such as acetone and the like, and aliphatic, cyclic andaromatic amines, and the like. Similar compounds can be found in TheChemistry of Clay-Organic Reactions by B. H. G. Theng, John Wiley &Sons, New York, 1974. These clays can have a triple-layer structurewherein a magnesium or aluminum octahedral layer is sandwiched betweentwo silica tetrahedral layers. Examples of lamellar clays are smecticclays such as, montmorillonite, saponite, beidellite, nontronite,hectorite stevensite, bentonite, or substituents, derivatives or amixture of these substances. and the like. These clays can be eithernatural or synthetic. Montnorillonite and bentonite are preferredlamellar clays.

Swelling mica is also a useful lamellar clay. Examples of swelling micaare chemically synthesized swelling mica such as SOMASIF (trade name,manufactured by CO-OP Chemical Co., Ltd., Tokyo, Japan) and tetrasilicicmica containing a lithium ion or a sodium ion in the interlayers,taeniolite, or substituents, derivatives or a mixture of thesesubstances.

The lamellar clay should have a cation exchange capacity (CEC) of about50 to about 200 milliequivalents (meq)/100 g of clay. If the cationexchange capacity is less than 50 meq/100 g of clay, the swelling of theclay layers cannot be sufficiently effected and exchange of cations withmodifying compounds, such as organic onium compounds, cannot be doneeffectively. If the cation exchange capacity exceeds 200 meq/100 g ofclay, the lamellar clay will not disperse finely due to higher bondstrength between the layers.

Commercially available purified bentonites are available under the tradename Polargel NF (American Colloid Company, Arlington Heights, Ill.) andothers can be prepared from a Wyoming source of sodium montmorillonitefeed stock (provided by Southern Clay Products Inc., Gonzales, Tex.).Sodium montmorillonite is preferred because organic onium modified claysprepared from this source display good dispersibility in solvents usedto prepare wet- and dry-spun polyurethane fibers. These clays have acation exchange capacity of about 90-100 meq/100 g of clay.

Prior to dispersion or modification of the lamellar clay, it may benecessary to subject the lamellar clay to shear by pulverizingtreatment, high speed shear cleavage of a wet type or a dry type, orultrasonic cleavage.

The interlayer separation in the lamellar clay can vary from about 8 Åto about 12 Å depending on the hydration of the clay. Preferably, thelamellar clay is modified to provide an interlayer distance of thelayers of the clay of at least 17 Å. The interlayer separation of thelamellar clay can be measured by x-ray diffraction. These preferredinterlayer distances provide for good delamination of the layers fromthe lamellar clay during modification and/or upon agitation. Gooddelamination can be exhibited by random distribution of the clay layers,i.e. no order in the layer arrangement, as well as, absence of x-raypeaks in the low 12-50 Å range measured after dispersion of the clay ina polyurethane.

Modification of a lamellar clay can be based on the replacement ofexchangeable inorganic ions in the lamellar clay. Alkaline or alkalineearth metal ions and the like in the lamellar clay can be removed bysubstitution, for example with ions from an organic onium compound byfirst expanding the clay in water. alcohol or a similar solvent. Sincethe metal ions have different capacities for exchange reactions,monovalent cations like Na⁺, K⁺ and the like are preferred. The ratio(CEC) of the organic onium ions to the layered clay is not specificallyrestricted; however, the amount of the organic onium ions should belarge enough for the substantially complete replacement of theexchangeable inorganic ions of the clay. Preferably, replacement is inan amount of about 0.7 to about 1.25 times (as equivalents).

Organic “onium” compounds can be primary, secondary, tertiary orquaternary ammonium compounds; pyridinium compounds; imidazoliniumcompounds; phosphonium compounds or sulfonium compounds. Preferredexamples of onium ions are N-((tallowalkyl)-bishydroxyethyl) methylammonium ion; 1-dodecylammonium ion, and N-((hydrogenatedtallowalkyl)-2-ethylhexyl)dimethyl ammonium ion, hexamethyleneimineammoniumn, methyl-1-hydrogenated tallow amidoethyl 2-hydrogenated tallowimidazolinium methyl sulfate and salts of dehydroabietylamine. By“tallow” is meant herein the fat from the fatty tissue of bovine cattleor sheep. Tallow contains (as glycerides): oleic acid, palmitic acid,stearic, myristic, and linoleic. Minor constituents of tallow arecholesterol, arachidonic, elaidic, and vaccenic acid. The most observedcharacteristic of tallow is its solidification point which ranges from40 to 46 degrees Centigrade. Further, tallow alkyl or hydrogenated tallwalkyl are terms used in commerce generally referring to mixing C₁₆ andC₁₈ alkyl groups obtained from tallow. The organic onium compounds havean onium ion at one terminal of the main chain and can have one or morelong alkyl chains or a bulky non-aromatic cyclic compound to increasethe clay interlayer separation upon substitution with metal ions. Themain chain can be a straight or branched carbon chain; it can have aring structure in part thereof. The other terminal of the main chain canhave a hydrogen atom or a group (or a derivative thereof) such as ahydroxyl group, amino group, carboxyl group, nitro group, and sulfonegroup. The main chain should preferably have 6 or more carbon atoms sothat the organic onium ion expands the interlayer distance of thelamellar clay to such an extent that the ionic interactions between thelayers are reduced. However, the main chain should preferably have lessthat 20 carbon atoms so that the organic onium ion has a good affinityfor an aprotic polar solvent, such as those noted herein.

There is no specific limitation on the method for producing organiconium modified clay so long as the exchangeable cation of the lamellarclay can be efficiently ion exchanged for an organic onium ion. Atypical process consists of mixing a lamellar clay with organic oniumions in a neat or mixed solvent selected from water, methanol, ethanol,propanol, isopropanol, ethylene glycol, 1,4-butanediol, and glycerin. Apreferred solvent for montmorillonite is water, methanol or ethanol, ora mixture thereof. For example, to a dispersion comprising from 1 to 5%by weight of the lamellar clay in water, a solution of a quaternaryammonium salt in an amount 0.5 to 1.5 times (as equivalents) as much asthat of the lamellar clay in terms of cation exchange capacity can beadded.

To prepare the fiber or film of the present invention, a lamellar clay,or a dispersion of the lamellar clay in an aprotic polar solvent iscontacted with a solution comprising a polyurethane and the same or adifferent aprotic polar solvent to form a polyurethane/clay dispersion.Preferably, the lamellar clay is modified to provide an interlayerdistance between the layers of the clay of at least 17 Å. Modification,for example with organic onium ions, can be accomplished as describedabove. The lamellar clay in the polyurethane/clay dispersion is in anamount of about 0.1 to about 12% by weight, preferably about 0.5 toabout 3% by weight, based on the solid component of the polyurethane.Preferably the same aprotic polar solvent is used for the claydispersion preparation as is in the solution comprising thepolyurethane. Solvents, such as dimethylacetamide (DMAc),dimethylformamide, N-methylpyrrolidone or the like are preferred withDMAc being most preferred. The aprotic polar solvent is a solvent forthe polyurethane only, but it is miscible with organic onium ions, ifpresent, and hence with a modified lamellar clay. Therefore, thesesolvents permit intimate mixing (at the molecular level) of thepolyurethane with the lamellar clay. Preferably upon contact with thepolyurethane solution, the lamellar clay is expanded with thepolyurethane (the polyurethane diffuses into the space between thelayers of the lamellar clay) such that the interlayer distance of thelamellar clay is greater than about 25 Å as measured in a driedpolyurethane film comprising such clay. Expansion can act to delaminatesome of the layers of the clay.

The polyurethane/clay dispersion is agitated with an amount of shearsufficient to further delaminate all or a portion of the layers of clayfrom the lamellar clay and from each other. This agitation can beapplied by high shear mixers, static mixers, such as Koch or Kenixmixers, media mills, sand mills, gear pumps or the like. Preferably,x-ray diffraction analysis of a dried film formed from thepolyurethane/clay dispersion shows no residual d(001) peaks and noexpanded d(001) peaks. The lack of these peaks indicate delaminationwith more than 1-2 polyurethaie molecules between the layers of theclay. Only broad x-ray scatter is observed supporting polyurethane/clayfilm or fiber having delaminated and well-dispersed layers.

Following agitation, dispersion of the lamellar clay in the polyurethaneis a state of dispersion in which the lamellar clay is delaminatedprimarily into individual layers at the molecular level. By“delaminated” is meant that the layers of the clay are exfoliated anddispersed in a continuous polymer matrix. The state of dispersion issuch that more than 50%, preferably more than 70% of the lamellar clayis dispersed as layers without forming a mass. Most preferably thelayers are individual layers or are groups numbering less than 5 layers(on average) orienting parallel to one another or randomly or both indispersions prior to fiber or film formation. When the polyurethane/claydispersion is formed into a fiber or a film, the delaminated layers areoriented in a direction parallel to the fiber or the film axis.Transmission Electron Microscopy (TEM) can be used to confirm that thelayers of the lamellar clay have delaminated into primarily individuallayers (about 10 Å thick×about 2000 Å diameter for montmorillonite) to afairly high degree and that these layers are highly oriented with filmor fiber spinning direction.

The polyurethane/clay dispersion can then be formed into fibers or film.For fibers, the polyurethane/clay dispersion can be wet- or dry-spuninto filaments from preferably the same solvent as was used for thepolyurethane polymerization reactions. The polyurethane/clay dispersioncan be spun as single filaments or can be coalesced by conventionaltechniques into multi-filament yarns.

Following or during spinning the solvent can be removed from the fibersvia conventional methods. Dry spinning of the fiber is preferred.

“Fibers” as used herein, mean filaments, fibers, and/or yarns preparedusing polyurethane. Threads of polyurethane of the present invention maybe covered or entangled with conventional nonelastic fibers (e.g. ofpolyamide, such as nylon, or polyester).

In order to form film, the polyurethane/clay dispersion can be solutioncast and then dried using conventional techniques. Preferably thesolution is cast and dried on a substrate, for example another polymer,such as polyethylene teraphthalate, Mylar® for example; glass, ceramic;or a fabric, such as spandex, or polyester, Dacron for example, cotton,nylon or the like. Coating fabrics with the films of the presentinvention can impart waterproof characteristics to such fabrics.

In the fibers and films of the present invention, the lamellar clay canbe contacted with the polyurethane alone or with other additives in aconcentrated slurry which is then incorporated in the fiber polymersolution stream or the film casting solution. Conventional agents can beadded for specific purposes. such as antioxidants, thermal stabilizers,UV stabilizers, pigments (for example titanium dioxide and the like),lubricating agents, other anti-tack agents (for example silicone oil,metal stearates, and the like), additives to enhance resistance tochlorine degradation (for example zinc oxide, magnesium oxide, and thelike), and the like, as long as such agents do not produce anantagonistic effect with the polymer or the organic onium modified clayof this invention.

Polyurethane fiber and film of the present invention exhibit a desirablereduction in tackiness or decrease in self adhesion. FIG. 1 is a plot ofthe work or the peel force (J/m²) to rupture a self adhesion bond ofpolyurethane film to polyurethane film versus the square root of time(min^(½)) at room temperature (see Example 4). Films with different andvarying amounts of organic onium modified lamellar clay were comparedwith a film containing no lamellar clay and a film containing unmodifiedlamellar clay. All films had no added surface lubricant. Sample 0 (solidline with solid circles) was the control and had no clay; Sample 1(dotted line with diamonds) had unmodified lamellar montmorilloniteclay; Sample 2A (solid line with triangles) had 3%N-(tallowalkyl)-bishydroxyethyl)methyl ammonium modifiedmontmorillonite; Sample 2B (dotted line with triangles) had 1%N-(tallowalkyl)-bishydroxyethyl)methyl ammonium modifiedmontmorillonite; Sample 5A (solid line with open circles) had 3%1-dodecyl ammonium modified montmorillonite; and Sample 5B (dotted linewith quartered squares) had 1% 1-dodecyl ammonium modifiedmontmorillonite. The graph illustrates the dramatic effect of organiconium modified lamellar clay on reducing the rate of tack build up.Samples having 1 and 3 wt. % modified lamellar clay (Samples 2B, 5B, 2Aand 5A) exhibit a significant reduction in tack growth when compared tothe control film (Sample 0). Even the film having unmodified clay(Sample 1) exhibited some tack reduction. On a true time basis, oneexample of the data reveals that it takes 96 hr aging with 3% modifiedlamellar clay to reach the tack that the control reached in 30 min. A 1%modified lamellar clay loading is slightly less effective than 3% butstill reduces the tack growth by over an order of magnitude.

FIG. 2 is a graphical representation showing tack growth as a functionof time for fiber at the core, the middle and at the surface of a spool(See Example 5). The graph illustrates that incorporation of themodified clay in the fiber decreases the amount of over-end takeofftension for fiber at the core, middle and surface of the spool overtime; the improvement being realized after several months of aging.

Thus, the present invention provides a method for reducing tack inpolyurethane fiber or film. The method comprises dispersing a lamellarclay into a polyurethane solution, agitating the solution to delaminateall or a portion of the layers from the clay and from each other, andforming the solution into a fiber or film. For the preparation of afiber, the solution can be wet- or dry-spun. The ingredients,dispersion, agitation and spinning are as described above. For thepreparation of a film, the solution can be cast and dried byconventional methods known to those of skill in the art.

The fiber and film of the present invention retain the desirableproperties of polyurethane fiber and film which does not incorporate alamellar clay, e.g. in modulus, tenacity, elongation, toughness, and thelike. (See Example 1)

The fiber and film of the present invention can be uncolored or it canfurther comprise a dye. By “uncolored” is meant that neither the fibernor the film nor any of its components has been contacted with a dye.The fiber or film of the present invention exhibits improved uptake andfixation of dyes. By preparing fiber or film using the processes of thepresent invention, a method for increasing the ability of polyurethaneto affix at least one dye is provided.

Dye can be used to offset the natural color of the lamellar clay infiber. Useful loadings of such dye can range from 100 ppb (0.00001%) to15% OWF (on weight of fiber).

Organic dyes found to be useful for purposes of the present inventioninclude acid, pre-metallized acid, cationic, disperse, direct andreactive dyes. Representative of acid dyes are: Acid Blue 25, Acid Red25, Acid Green 23, Acid Red 266, Acid Red 361, Acid Yellow 49, AcidYellow 198, Acid Black 194 and Nylanthrene Black GLRT. Representative ofpre-metallized acid dyes are: Acid Yellow 116, Acid Orange 162, AcidBrown 226, Acid Red 251, Acid Blue 171, Acid Black 131, Acid Black 107and Acid Black 132. Representative of cationic dyes are: Cationic Blue77, Cationic Blue 3, Cationic Yellow 53, Cationic Yellow 11, CationicRed 29, Sevron Blue GBR, Sevron Black JON and Astrazon Black FSW.Representative of disperse dyes are: Disperse Blue 79. Disperse Red 60.Disperse Red 167, Disperse Yellow 23, Disperse Yellow 114, Foron BlackEDC and Intrasil Black HFE. Representative of direct dyes are: DirectYellow 106, Direct Red 89, Direct Blue 98 and Direct Black 22.Representative of reactive dyes are: Reactive Yellow 86, Reactive Red 2,Reactive Blue 4 and Reactive Black 5.

Fibers of the present invention, or fabrics containing the fibers of thepresent invention, or films of the present invention can be dyed withcombinations of more than one dye of the same class or combinations ofdyes from different classifications. The dye lists given above are notmeant in any way to limit the dyes useful with the present invention.The “Color Index, 3rd Edition, and its Additions and Amendments” providegeneric names for classifying commercial dyes and pigments with respectto usage. Where supplied by the vendor C.I. generic names are givenabove. The cases where C.I. names are not used indicate the vendor haschosen not to identify the C.I. name or that the dye as supplied is amixture of more than one dye of that class (e.g., many of the blackdyes).

An uncolored fiber or an uncolored film can by dyed after formation, thedye can be introduced while in the process of forming the fiber or film,or the fiber or film can be dyed both during and after the process offormation of the fiber or film.

If the fiber or film is dyed after formation of the fiber, the processas described above for preparing the fiber or film is used and furthercomprises the step of contacting the fiber with a dye to form a dyedfiber or a dyed film. The fiber can be dyed prior to knitting into afabric or after knitted into a fabric. Contact of the fiber, or thefabric, or the film with the dye can be by conventional methods known tothose skilled in the art.

In another embodiment of the present invention the dye can be introducedwhile in the process of forming the fiber or film. In this process apolyurethane solution is contacted with a lamellar clay, preferablymodified with onium ions, and a dye. Prior to contact with each other, adye solution or dispersion, a polyurethane solution and a claydispersion are prepared.

The dye solution or dispersion comprises an organic dye, preferably awater-soluble acid or tationic organic dye, which is dissolved in water,preferably deionized water, alcohol or other solvents such as acetone oracetic acid. If necessary the dye can be dissolved in the solvent belowthe boiling point of the solvent. Suitable acid or cationic dyes aredescribed above. Heating the water to an elevated temperature, e.g., 40°C. to 90° C. can also be done in order to dissolve the dye. However,many dyes are also soluble in cold water so that use of the heated wateris an optional feature depending on the dye used. The acid dyes shouldhave an amine or other functionality that can be converted to the saltstructure upon treatment with mineral or organic acids. It is preferredthat the dyes have good solubility in solvents like water or alcoholthat expand the lamellar clay. Preferably, the dye solution ordispersion further comprises an organic onium compound, as describedabove.

The clay dispersion is prepared by dispersing a lamellar clay in asolvent such as water, preferably deionized water, alcohol or a similarcompound such as acetone or acetic acid. Preferably, the clay isdispersed in the same solvent as used in the dye solution.

The clay dispersion is then contacted with the dye solution or dyedispersion, preferably with stirring to form a first dye/claydispersion. As a result of this contact, the dye becomes ionicallyassociated with the clay. Preferably, the dyes and any organic oniumions present used to exchange cations are always used on an equal molarbasis or slightly less than equal molar basis so that the lamellar clayhas an interlayer separation of 20 Å or more. The dye and any oniumcompound used for exchange reactions can be substituted on the cationexchange basis from 50/50 to 1/99 range. The selected range depends onthe color strength of the dyes needed for coloring the fiber. There isno specific limitation on the method for producing the first dye/claydispersion wherein the dye solution further comprises the organic oniumions so long as the exchangeable cation of the clay can be efficientlyion exchanged for the organic onium ions thus forming an organic oniummodified lamellar clay having a dye ionically associated therewith. Atypical process consists of mixing the lamellar clay with the dyesolution in a neat or mixed solvent selected from water, methanol,ethanol, propanol, isopropanol, ethylene glycol; 1,4-butanediol, andglycerin. A preferred solvent for montmorillonite is water, methanol orethanol, or a mixture thereof. For example, to a dispersion containingfrom about 1 to about 5% by weight of the lamellar clay in water, a dyesolution having a quaternary ammonium salt therein in an amount 0.5 to1.0 times (as equivalents) as much as that of the lamellar clay in termsof cation exchange capacity can be added.

Alternatively, a dye solution without the organic onium compound can beadded to the clay dispersion first followed by contact with an oniumsalt solution provided that the amount of dye solution (on an exchangebasis) is low and the clay does not flocculate after the addition of thedye solution. The treatment with onium salt solution is done later toflocculate the clay (pigment).

Next, a dyed clay is recovered, preferably as a solid, from the firstdye/clay dispersion by filtering, washing, heating or some combinationthereof.

After the dyed clay is recovered, it is dispersed in an aprotic polarsolvent miscible with any organic onium ion present and hence with themodified lamellar clay to form a second dye/clay dispersion. Tie solventcan be the same or a different solvent from the solvent used to dissolvethe polyurethane described below. Solvents, such as dimethylacetamide(DMAc), dimethylformamide, N-methylpyrrolidone or the like are preferredwith DMAc being most preferred.

To form the polyurethane solution, the polyurethane is dissolved in thesame or a different aprotic polar solvent, as described above,preferably the same solvent as used in the preparation of the seconddye/clay dispersion, most preferably. DMAc, to form the polyurethanesolution. Alternatively, the polyurethane can already be in solutionform as a result of its polymerization conditions.

The polyurethane solution is next contacted with the second dye/claydispersion to form a dye/clay/polyurethane dispersion. The aprotic polarsolvent(s) used in both the polyurethane solution and the seconddye/clay. dispersion permit intimate mixing (at the molecular level) ofthe polyurethane with the dyed organic onium modified lamellar clay.Preferably upon contact, the distance between the layers of the dyedclay are expanded with the polyurethane such that the interlayerdistance of the dyed clay is greater than about 25 Å.

The dye/clay/polyurethane dispersion is agitated with an amount of shearsufficient to further delaminate all or a portion of the layers from thelamellar clay and from each other. This agitation can be applied by highshear mixers, media mills, sand mills, gear pumps or the like.Preferably, x-ray diffraction analysis of a dried film formed from sucha dispersion shows no residual d(001) peaks and no expanded d(001)peaks. The lack of these peaks indicate delamination with more than 1-2polyurethane molecules between the layers of the clay. Only broad x-rayscatter is observed supporting a dye/clay/polyurethane dispersion havingdelaminated and well-dispersed layers.

Following agitation dispersion of the dyed organic onium modifiedlamellar clay in the polyurethane is a state of dispersion in which thedyed organic onium modified lamellar clay is divided primarily intoindividual layers at the molecular level. The state of dispersion issuch that more than 50%, preferably more than 70% of the dyed organiconium modified lamellar clay is dispersed without forming a mass. Mostpreferably the layers are individual layers or are groups of less than 5layers (on average) orienting parallel to one another or randomly orboth. When the dye/clay/polyurethane dispersion is formed into a film ora fiber, these individual layers delaminated from the dyed organic oniummodified lamellar clay are oriented in a direction parallel to the filmor fiber axis. TEM can be used to confirm that the layers of thelamellar clay have delaminated into individual layers to a fairly highdegree (about 10 Å thick×about 2000 Å diameter for montmorillonite) andthat these layers are highly oriented with the film or with the fiberspinning direction.

Finally, the dyed/clay/polyurethane dispersion is spun into fibers ordried as a film. The dye/clay/polyurethane dispersion can be wet- ordry-spun into fibers from the same solvent as was used for thepolyurethane polymerization reactions. The dye/clay/polyurethanedispersion can be spun as single fibers or can be coalesced byconventional techniques into multi-filament yarns. Following or duringspinning the solvent is removed from the fibers via conventionalmethods. Dry-spinning is preferred.

Another benefit of dyeing in the manner described immediately above isthat it can be used to offset the natural color of the lamellar clay.For example, a small amount of blue dye can offset any yellowness of thefibers.

Dye can be introduced while in the process of forming the fiber or film,as described above, and a second dye can be applied after fiber or filmformation. Thus, the process of the present invention immediately abovecan further comprise contacting the fiber spun or film cast from thedye/clay/polyurethane dispersion with a second dye. The spun fiber canbe dyed prior to knitting into a fabric or after knitting into a fabric.Dyeing can be by conventional means known to those of skill in the art.

Yarn and fabric made of the fiber of the present invention and film ofthe present invention exhibit increased color uptake (up to 50% more dyeuptake with acid dyes) and washfastness. The increased dye uptake andwashfastness leads to decreased “grin-through” when fibers are used inblend fabrics, e.g. in fabrics containing, for example, polyamide orpolyester fibers in addition to the polyurethane fibers.

The fiber and film of the present invention retain the desirableproperties, of polyurethane which does not incorporate an organic oniummodified lamellar clay, e.g. modulus, tenacity, elongation, toughness,and the like are maintained.

EXAMPLES

Polyurethane referred to in the following examples (unless otherwisenoted) is a polyurethaneurea made from poly(tetramethyleneether)glycol(PO4G). methylene-bis(4-phenylisocyanate)(MDI) and a mixture of ethylenediamine (EDA) and 2-methyl-1,5-diaminopentane (MPMD) and is availablefrom E. I. du Pont de Nemours and Company, Wilmington, Del. The numberaverage molecular weight of PO4G was about 1800, the capping ratio (themolar ratio of MDI to PO4G) was 1.7, and the molar ratio of EDA to MPMDwas 90/10. The NCO content of the isocyanate-capped polyether was about2.4%. The NCO content can be measured by the method of S Siggia,“Quantitative Organic Analysis via Functional Group”, Third Edition,Wiley and Sons, New York, pp., 559-561 (1963).

The following organic onium modified lamellar clays used in the exampleswere either prepared as described below or purchased from the indicatedsources. Clay powders were dried overnight in a vacuum oven at80° C. 6%solids dispersion were made with DMAc solvent using a homogenizer mixer(2.6 g clay plus 40 g DMAc).

Sample No. Montmorillonite Clay Designation 1 “Polargel” NF: unmodifiedsodium montmorillonite (American Clay Company, Arlington Heights, IL) 2(N-(tallowalkyl)-bishydroxyethyl)methyl ammonium modifiedmontmorillonite (Southern Clay Products, Inc., Gonzales, TX) 3 “Claytone40” dimethyl di-hydrogenated tallow ammonium modified montmorillonite(Southern Clay) 4 methyl-1-hydrogenated tallow amidoethyl 2-hydrogenatedtallow imidazolinium methyl sulfate modified montmorillonite(Imidazolinium ion source is Varisoft ® 445 from Witco Chemical Co.) 51-dodecylammonium modified montmorillonite 6 N-((hydrogenatedtallowalkyl)-2-ethylhexyl) dimethyl ammonium modified montmorillonite(Southern Clay) 7 hexamethyleneimine ammonium modified montmorillonite 8dehydroabietylamine modified montmorillonite

Preparation of Sample 4

A 5% water dispersion of “Polargel” NF (sodium montmorillonite) wasprepared by dispersing 50 g of “Polargel” NF in 1000 g of deionizedwater using a high-speed homogenizer mixer. To that mixture was added asolution of 55 g of “Varisoft” 445 (from Sherex division of WitcoChemicals) which is a 75% solids quaternary ammonium salt containing 25%isopropanol. “Varisoft” 445 is 1-methyl-hydrogentated tallow amidoethyl2-hydrogentated tallow imidazolinium methylsulfate. “Varisoft” 445 hadbeen dissolved in an additional 200 ml of isopropanol before adding tothe clay dispersion. The organic onium modified clay flocculated andprecipitated immediately when the ammonium salt solution was added. Thisslurry was stirred and temperature raised to 80° C. for one hour. Theorganic onium modified clay was isolated by filtration, reslurried twicein 1 liter of water and reisolated by filtration. The solids were dried,granulated and then “air-micronized” to a particle size of <3 microns.

Preparation of Sample 5

A 5% water dispersion of “Polargel” NF (sodium montmorillonite) wasprepared by dispersing 50 g of “Polargel” NF in 1000 g of deionizedwater using a high-speed homogenizer mixer. To that mixture was added asolution of 55.5 g of 1-dodecylamine which had been dissolved in 500 mlof water and neutralized with 30 g of 37% hydrochloric acid solution.The organic onium modified clay flocculated and precipitated immediatelywhen the ammonium salt solution was added. This slurry was stirred andtemperature raised to 80° C. for one hour. The organic onium modifiedclay was isolated by filtration, reslurried twice in 1 liter of waterand reisolated by filtration. The solids were dried, granulated and then“air-micronized” to a particle size of <3 microns.

Preparation of Sample 7

A 5% water dispersion of “Polargel” NF (sodium montmorillonite) wasprepared by dispersing 50 g of “Polargel” NF in 1000 g of deionizedwater using a high-speed homogenizer mixer. To that mixture was added asolution of 25.8 g of hexamethyleneimine dissolved in 400 ml of waterand neutralized with 30 g of 37% hydrochloric acid solution. The organiconium modified clay flocculated and precipitated immediately when theammonium salt solution was added. This slurry was stirred andtemperature raised to 80° C. for one hour. The organic onium modifiedclay was isolated by filtration, reslurried twice in 1 liter of waterand reisolated by filtration. The solids were dried, granulated and then“air-micronized” to a particle size of <3 microns.

Preparation of Sample 8

169.4 g of sodium montmorillonite clay (provided by Southern ClayProducts, Inc., as a 3.08% solid dispersion in water with a cationexchange capacity of 90 meq/100 g) was heated to 70° C. 43.52 g ofdehydroabietylamine was acidified with 25 ml of acetic acid and the saltwas dissolved in 500 ml of deionized water. The amine salt solution wasadded to the clay dispersion under vigorous stirring conditions. Theflocculated clay dispersion was stirred for another hour at 70° C. Theclay was filtered, washed twice by suspending in deionized water,stirred and heated to 70° C. and filtered. The clay was dried at 110° C.under vacuum. It was then air micronized to less than 10 micronparticles sizes and dispersed in DMAc at 5 wt % solid concentrationusing a Silverson Homogenizer.

Example 1 Fiber Tensile Test and Fiber Cyclic Test 300%

Fiber comprising onium modified montmorillonite was prepared bycombining a 36% polyurethane solution in DMAc with an 8% DMAc dispersionof montmorillonite clay modified with(N-tallowalkyl)-(bishydroxyethyl)methyl ammonium at proportions toprovide dried polymer containing 1 wt % and 2 wt % of the clay additive.The 8% modified clay in DMAc dispersion was prepared by high shearmixing with a homogenizer mixer. The mixture of this dispersion with thepolyurethane solution was prepared with low shear paddle mixing followedby circulation of this mix through a gear pump for 2-4 hours.

The solutions described above, plus a separate control solutioncontaining no clay additive, was dry spun into 15 dtex yarns in aconventional apparatus. The solution was metered through spinneretorifices into a spin shaft in which the solution formed filaments as theDMAc solvent evaporated. A flow of heated nitrogen gas was supplied tothe shaft to evaporate the DMAc. The threadlines exited through thebottom of the shaft. A silicone oil finish lubricant was applied to thethreadlines by a kiss roll applicator to provide an addition of about3.5% based on weight of threadline. The yarn was then wound up at aspeed of about 840 meters per minute.

Physical properties of the 15 dtex polyurethane yarns produced by theprocedures described above and containing 1 and 2% onium modifiedmontmorillonite, in accordance with the invention, were compared with acontrol yarn containing no montmorillonite. Tables 1 and 2 summarize thedata. Strength and elastic properties of the polyurethane were measuredin accordance with the general method of ASTM D 2731-72. Fiber Tensiletest data was reported in GPD (grams per denier), Elongation @ Max (orbreak) and Toughness (GPD). For the zero-to 300% elongation cycle test,three filaments 2 inch (5 cm) gauge length were used. The fibers werecycled five times at a constant elongation rate of 800% per minute andthen held at the 300% extension for half a minute after the fifthextension. “Unload power” is reported herein in deciNewtons/tex (DN/TEX)and is the stress measured at a given extension during the fifth unloadcycle. Percent set was measured on samples that had been subjected tofive 0-300% elongation-and-relaxation cycles. The percent set (%S) wasthen calculated as %S=100(L_(f)−L_(o))/L_(o), where L_(o) and L_(f) arerespectively the filaments length, when held straight without tension,before and after the fifth elongation/relaxation cycles.

TABLE 1 Initial Modulus Break Tenacity Elongation Toughness % Clay GPDGPD @Max (%) GPD 0% 0.082 1.184 429 1.460 1% 0.071 1.224 463 1.581 2%0.104 1.373 484 1.918

TABLE 2 Unload Unload Unload Unload Unload % Stress % @200% @167% @100%@60% @33% % Stress Clay dn/tex #1000 dn/tex #1000 dn/tex Decay % Set 0%74.5 53.5 30.9 16.4 5.4 25.1 15.6 1% 67.3 47.7 26.9 13.3 3.3 25.7 17.82% 71.8 50.8 27.6 12.1 1.6 26.2 18.6

Example 2 Different wt % Clay Samples

The physical properties of solution cast (and dried) polyurethanesamples comprising 0, 1, 3, 5, and 12 wt % dodecylammoniummontmorillonite were measured using standard elastomeric conditions.Solution cast and dried films (3-7 mil thick) showed that goodelastomeric properties were maintained for all samples. The increase intensile modulus, yield modulus and modulus at 10% elongationdemonstrated a reinforcing property of these clays in thick films. Databelow in Table 3 was obtained by ASTM Method D-882. (kpsi=1000×poundsper square inch)

TABLE 3 Tensile 10%E Elong. Ultimate % Modulus Yield Mx Break Modulus @Elongation Clay (kpsi) (kpsi) (kpsi) (kpsi) (kpsi) yield% % 0 0.7420.375 5.270 5.050 0.139 44.1 860 1 0.800 0.391 5.250 5.020 0.154 41.5858 3 1.130 0.450 5.101 5.000 0.189 40.4 858 5 1.754 0.465 3.980 3.7200.216 34.8 764 12 3.082 0.511 4.880 4.870 0.336 21.1 949

Example 3 Hand Peel Test for Tack Reduction of Film

30 g of polyurethane solution (17.5% solids in DMAc) was separatelymixed with a DMAc dispersion containing 2.7 g of Samples 1-7 of the claylisted above (prior to Example 1) using a homogenizer and mixing atmoderate speed for 5 min. The calculated clay content on a dry polymerbasis was 3% by wt. Sample 0 was a control with no clay added. Filmswere made by draw knife casting (6-10 mil) onto 5 mil Mylar®polyethylene terephthalate film. Films were dried 30 min in 60° C. aircirculating oven and then overnight at 80° C. in a vacuum oven (20″vacuum).

Film strips of the Mylar®/polyurethane laminate were cut and placedpolyurethane face to face overnight under the pressure of a two poundweight. Hand-held peels as shown in Table 4 gave the following ratings(0-10) with 10 being the most adhered, 0 being no significant bond.

TABLE 4 Sample Peel Rating 0-control 10 (some separation from theMylar ® film) 1 8 2 3 3 4 4 5 5 3 6 4 7 9

Example 4 Reduction in Tack in Film

Segmented polyurethane polymer solutions in dimethylacetamide (DMAc) ata 7% concentration (with and without additives) were cast onto Mylar®polyethylene terephthalate flexible film and onto a glass surface anddried to leave a film of approximately 3 μm thick. For improved adhesionto the substrates, corona treated Mylar® and glass treated withaminopropylsilane were used. Sample 0 (the control) is polyurethanehaving no clay dispersed therein. Sample 1 is polyurethane havingunmodified sodium montmorillonite dispersed therein. The other samplesare polyurethane having modified montmorillonite dispersed therein. Theother samples are: polyurethane having 1 dodecylammonium modified claydispersed therein (Sample 5A is 3% clay and Sample 5B is 1% clay) andpolyurethane having [N-(tallowalkyl)-bishydroxyethyl)methyl ammonium]dispersed therein (Sample 2A is 3% clay and Sample 2B is 1% clay). Allmodified and unmodified samples dispersed well in DMAc and in thepolyurethane with the clay remaining dispersed in the solution and notsettling to the bottom with time. Measurements of the 90° peel forcewere obtained on strips 2 cm wide and 10 cm long on an Instron tensiletester at a rate of 0.3 mm/s. These tests were performed after variousannealing times aging at 24° C. The work of detachment per unit area ofinterface (W) was calculated from the peel force (P) measured at a peelangle of 90° C. W=P(1−cos θ)/w, for θ=90°, W=P/w. The values obtainedfor W were found to have a pronounced nonlinear time dependence, withapproximate power law behavior (tn) and data are plotted versus squareroot of time. Table 5 presents the peel force data (J/m²) as a functionof the square root of time of each of the samples. (See also FIG. 1).

A related test method and description of an expected linear growth ofpeel force with t^(½) is discussed in W. F. Reichert and H. R. Brown,Polymer, 34, 2289 (1993). Further discussion of a method of measuringself-adhesion of spandex polymer as a film is found in J. G. Van Alsten,et al. Macromolecules, 1995, 28, 7019 and in B. B. Sauer, C. R.Gochananour, and J. G. Van Alsten, ACS PMSE Preprints, 8/96 National ACSMeeting, Orlando, Fla.

TABLE 5 Time (min)^(½)) Peel Force Sample Number (J/m²) 0 5A 2A 5B 2B 117.700 3.1620 *0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 14.7005.4470 53.900 9.4870 186.20 36.332 98.000 18.200 5.8800 17.321 14.70037.947 24.500 75.895 7.3500 17.321 17.321 17.150 37.947 37.947 29.40075.895 75.895 18.000 18.000 14.500 18.200 18.200 123.00 37.947 *Timezero is taken in the plot as having zero peel force to separate film.

Example 5 Reduction in Tack in Fiber

15 denier polyurethane fiber comprising 2%(N-(tallowalkyl)bishydroxyethyl)methyl ammonium modified montmorilloniteclay was spun from a DMAc solution and the fiber surface treated withconventional silicone lubricants before winding and storing on a spool.Wound samples were then aged and were compared with a control using theover-end take-off method described below after ambient temperatureaging. Over-end take-off tension, a measure of the tackiness of aspandex yarn, was determined herein in accordance with the proceduredisclosed in Hanzel et al., U.S. Pat. No. 4,296,174, Col. 4, lines20-45, with reference to FIG. 6 of the patent. In accordance with thistechnique, measurement was made of the average tension required toremove a 183-meter sample of spandex yarn from a supply package of theyarn at a delivery rate of 45.7 meters per minute. The fiber near thecore of the spool sees the most pressure and thus builds tack fasterthan the outside. If too high tack is reached the fiber stretches duringspinning and distorts the fiber and/or breaks the fiber. It is felt thata take-off tension of >1 g would give knitting and handling problems inremoving fiber from the spool.

Data showed that clay additive reduced the increase of tack over time;the improvement being realized after several months of aging. Thisindicated extended shelf stability. (See also FIG. 2.)

TABLE 6 Time (mos.) @ambient Take-off Tension (in grams) temp. Core CoreMiddle Middle Surface Surface Aging Control Sample Control SampleControl Sample 0 .40 .40 0.28 0.28 0.07 0.07 2 .44 .44 0.30 0.30 0.110.11 10 .86 .60 0.68 0.50 0.18 0.09

Example 6 Cationic Dyeability of Polyurethane Films Containing 1% Clay

Polyurethane films were prepared by placing 5.0 grams of 12 wt %polyurethane in a DMAc solution into circular aluminum pans. Thepolyurethane/DMAc solution in pans were placed in an oven at 100° C.under 2″ Hg vacuum with a slight nitrogen purge overnight to form thefilms. The films were then removed from the aluminum pans for subsequenttesting. The control films were prepared as stated above. Polyurethanefilms containing 1% by weight of (N-(tallowalkyl)-bishydroxyethyl)methylammonium modified montmorillonite clay were prepared by first mixing theclay in DMAc and then adding the clay/DMAc to make the 12%polyurethane/DMAc solution. Mixing was done in a Waring blender. Thepolyurethane/clay films were then prepared as stated above.

The polyurethane and polyurethane/clay films were sewn insidecationically dyeable polyester fabric pockets. The ratio of polyurethanefilm to polyester fabric was 10:90 by weight. The polyurethane/polyestersamples were prescoured at a 40:1 liquor ratio by placing in an aqueoussolution of 1 g/l Merpol LFH and 0.5 g/l tetrasodiumpyrophosphate at110° F. heating to 180° F. at a rate of 30° F./min, running for 30minutes at 180° F., cooling to 170° F., and rinsed until clear with roomtemperature water.

The polyurethane/polyester samples were cationically dyed using 6.0% onweight fabric (o.w.f.) Sevron Blue GBR or Sevron Yellow R (Crompton &Knowles) at a 40:1 liquor ratio. The aqueous dyebath was set at 80° F.with 3.0 g/l sodium sulfate and acetic acid added to adjust the pH to4.5. The cationic dye was dissolved in the dyebath, the sample added,and the temperature raised to 239° F. at a rate of 30° F. min, and dyedfor 1 hour The dye bath was then cooled to 170° F., rinsed with wateruntil clear and drained.

The dyed samples were placed in an aqueous bath at 110° F. containing1.0 g/l Merpol LFH and 2.5 g/l acetic acid, heated to 160° F. at a rateof 3° F./min, run for 20 minutes, rinsed clear and drained. The sampleswere then air dried.

A Multifiber Strip #30 was sewn to each of the polyurethane/polyestersamples and the samples subjected at an AATCC 2A Washfastness test.Staining of the multifiber strip was minimal with 4 or 5 ratings in allcases.

Test: 2A Washfastness (Staining)

Pieces of the fabrics were given a standard wash stain test (AmericanAssociation of Textile Chemists and Colorists Test Method 61-1989,“Color fastness to Laundering, Home and Commercial; Accelerated”; 2Aversion), which is intended to simulate five washes at low-to-moderatetemperatures. The test was run in the presence of a nylon was visuallyrated. In the ratings, 1 and 2 are poor, 3 is fair, 4 is good, and 5 isexcellent.

The polyurethane films were then removed from the polyester pockets andtheir color measured. Color measurements were done using a Macbeth ColorEye 2020 with Optimatch Software. The Colorant Strength results obtainedwere:

Standard a) no clay, Sevron Blue GBR Trial a) 1% clay, Sevron Blue GBRCHROMATIC - 2815% of Standard at 660 nm APPARENT - 2387% of StandardStandard b) no clay, Sevron Yellow R Trial b) 1% clay, Sevron Yellow RCHROMATIC - 236% of Standard at 420 nm APPARENT -327% of Standard

The polyurethane films comprising clay dyed to 23-28×deeper blue and2-3×deeper yellow than the polyurethane films without the clay.Additionally, the polyurethane film without clay was nearly completelycleared of the Sevron Blue GBR.

Example 7 “Grin Through” and Glitter Reduction in Dyed Fabrics withPolyurethane Containing Clay

Circular knit Lawson tubing fabrics were knit composed of 85% by weightcationically dyeable polyester (70-34 textured yarn) and 15% by weightof polyurethane, 40d or 15% by weight of polyurethane yarn containing 2%by weight of (N-(tallowallkyl)-bishydroxyethyl)methyl ammonium modifiedmontmorillonite clay.

The two fabrics were cationically dyed using the same procedures and 2Awashed as in Example 6: however, liquor ratios of 20:1 and 6.0% o.w.f.dye were used in this example. The cationic dyes used were: i) SevronBlue GBR, ii) Sevron Yellow 8GMF, iii) Basacryl Red GL and iv) SevronBlack JON.

In all cases, the fabrics containing the polyurethane yarn whenstretched exposed the undyed or lightly stained polyurethane yarn (i.e.,“grin through”). The undyed polyurethane yarn also reflects visiblelight causing the glitter effect. Both “grin through” and glitter areobjectionable in most dyed fabrics. This effect is most noticeable inthe blue, black and red fabrics, but rather difficult to see in thebright yellow fabric.

The fabrics with the polyurethane yarn containing the 2% clay resultedin the polyurethane yarns being dyed. Consequently, the dyed fabricswhen stretched did not “grin through” undyed or lightly stainedpolyurethane yarn. Additionally, the polyurethane yarn being dyednoticeably reduced the amount of reflected light, i.e. reduced theglitter. The Sevron Black JON is a combination dye composed of a numberof individual cationic dyed shades (usually blue, red and yellowshades). The polyurethane with clay when dyed with this black dyed to ared brown shade (meaning the blue shade of the combination black did notgo into the polyurethane). While a union dye (both fibers dyed to thesame shade) did not result for this black, both “grin through” andglitter were reduced greatly.

Example 8

100 g of sodium montmorrillonite clay (provided by Southern ClayProducts, Inc. as a dispersion in water with a cation exchange capacityof 90 meq/100 g) was dispersed in deionized water. Deionized water wasadded to the dispersion to make it 3 weight percent clay concentration.The dispersion was heated to 70° C. 20.55 g of dehydroabietylamine wasacidified with 15 ml of glacial acetic acid, and the salt was dissolvedin 500 ml of deionized water. 6.59 g of Nile Blue dye was dissolved in300 ml of water. The amine salt and dye solutions were mixed and addedto the clay dispersion under vigorous stirring conditions. Theflocculated clay dispersion was stirred for another hour at 70° C. Theclay was filtered and washed twice by suspending in deionized water,stirring and heating to 70° C. and filtering. The blue pigment was driedat 110° C. under vacuum. The pigment was air micronized to less than 10micron particle sizes and dispersed in DMAc at 5 wt % concentrationusing Silverson Homogenizer. The clay pigment prepared under theseconditions has an interlayer separation of 22 Å and has about 5.2% NileBlue dye attached to the clay on weight basis.

Example 9

Addition of an organic onium modified clay to a polyurethane cansometimes impart a yellow color to the composition relative to thepolyurethane without the organic onium modified clay. Surprisingly smallamounts of pre-dyed clay when added to the organic onium modifiedclay/polyurethane composition largely offsets the yellowness due to thepresence of the organic onium modified clay as shown below.

The organic onium modified clays used in this example are Wyoming clayswith surface treatments of: A—dehydroabietylamine (ca. 20.4% by weightof the organic onium modified clay) andB—N-(tallowalkyl)-bishydroxyethyl)methyl ammonium andC—dehydroabietylamine and Nile Blue (an organic onium modified clay dyecontent of 5.2%).

A polyurethane solution and clays modified with A, B, and C were mixedand made into films via the procedure given in Example 6. YellownessIndices (Y.I.) according to ASTM 1925 were measured using a Hunter LabColorQUEST colorimeter operated in the transmittance mode, using theHunter Lab scale and a 10 degree observer. The polyurethane/organiconium modified clay compositions and their respective Y.I. values aregiven in Table 7 below.

TABLE 7 Sample A Sample B Sample C Weight % Weight B Parts Per MillionY.I. 0 0 0 1.02 1.0 0 0 2.84 2.0 0 0 4.17 3.0 0 0 4.21 5.0 0 0 6.04 01.0 0 2.57 0 2.0 0 2.93 0 3.0 0 3.89 0 5.0 0 6.20 0 0 50 1.94 0 0 1001.70 0 0 500 0.61 1.0 0 10 0.95 1.0 0 25 0.26 1.0 0 50 0.12 2.0 0 101.42 2.0 0 25 0.70 2.0 0 50 0.86 3.0 0 10 1.22 3.0 0 25 2.12 3.0 0 501.61 5.0 0 10 2.26 5.0 0 25 2.50 5.0 0 50 2.16 0 1.0 10 1.36 0 1.0 250.72 0 1.0 50 1.46 0 2.0 10 2.16 0 2.0 25 1.35 0 2.0 50 0.80 0 3.0 102.35 0 0 25 2.51 0 3.0 50 0.98 0 5.0 10 3.24 0 5.0 25 4.54 0 5.0 50 3.72

As shown by the above data, the addition of component C (pre-dyedorganic onium modified clay) in very low amounts to thepolyurethane/organic onium modified clay composition significantlylowers the yellowness of the composition.

What is claimed is:
 1. A process for preparing a fiber or film comprising a wet- or dry-spun product or a solution cast product, which comprises a polyurethane and layers delaminated from a lamellar clay, said layers being dispersed in said polyurethane, the process comprising the steps of: (a) contacting a solution comprising a polyurethane and an aprotic polar solvent with a lamellar clay, or with a dispersion of said lamellar clay in the aprotic polar solvent, to form a polyurethane/clay dispersion; (b) agitating the polyurethane/clay dispersion sufficient to delaminate all or apportion of said layers from the lamellar clay and from each other; and (c) wet- or dry-spinning the polyurethane/clay dispersion or solution casting the polyurethane/clay dispersion to form a fiber or film.
 2. The process of claim 1 further comprising contacting the fiber with a dye.
 3. The process of claim 1 wherein the polyurethane comprises 85% by weight of a segmented polyurethane.
 4. The process of claim 1 wherein the aprotic polar solvent is dimethylacetamide.
 5. The process of claim 1 wherein the lamellar clay and the polyurethane are mixed in a ratio of about 0.1 to about 12 parts by weight for the lamellar clay to about 88 to about 99.9 parts by weight for the polyurethane.
 6. The process of claim 1 wherein the dye is an acidic, cationic, direct, disperse, reactive or pre-metallized dye.
 7. The process of claim 1 wherein the lamellar clay is at least one selected from the group consisting of: smectite clays comprising montmorillonite, saponite, beidellite, nontronite, hectorite, stevensite, bentonite; and swellable mica.
 8. The process of claim 7 wherein the lamellar clay has a cation exchange capacity of about 50 to about 200 meq/100 g.
 9. The process of claim 1 wherein the lamellar clay is modified to provide an interlayer distance of said layers of at least 17 Å.
 10. The process of claim 9 wherein the lamellar clay is modified with an organic onium ion.
 11. The process of claim 10 wherein the organic onium ion is at least one selected from the group consisting of: a primary ammonium ion, a secondary ammonium ion, a tertiary ammonium ion, a quaternary ammonium ion, a pyridinium ion, an imidazolinium ion, a phosphonium ion and a sulphonium ion.
 12. The process of claim 1 wherein the layers are individual layers or are groups numbering less than five layers on average.
 13. A process for preparing a dyed fiber comprising a wet- or dry-spun product which comprises a polyurethane, layers delaminated from a lamellar clay and a dye, said layers and said dye being dispersed in said polyurethane, the process comprising the steps of: (a) contacting a clay dispersion comprising a lamellar clay and a solvent with a dye solution or a dye dispersion comprising an organic dye to form a first dye/clay dispersion; (b) recovering a dyed clay from the first dye/clay dispersion; (c) contacting a solution comprising a polyurethane and an aprotic polar solvent with a second dye/clay dispersion comprising the dyed clay and the aprotic polar solvent to form a dye/clay/polyurethane dispersion, (d) agitating the dye/clay/polyurethane dispersion sufficient to delaminate all or a portion of said layers from the lamellar clay and from each other; and (e) wet- or dry-spinning the dye/clay/polyurethane dispersion to form a dyed fiber.
 14. The process of claim 13 wherein the polyurethane comprises 85% by weight of a segmented polyurethane.
 15. The process of claim 13 wherein the lamellar clay and the polyurethane are combined in a ratio of about 0.1 to about 12 parts by weight for the lamellar clay to about 88 to about 99.9 parts by weight for the polyurethane.
 16. The process of claim 13 wherein the aprotic polar solvent is dimethylacetamide.
 17. The process of claim 13 wherein the dye is a water-soluble acidic or cationic dye.
 18. The process of claim 13 wherein the lamellar clay is at least one selected from the group consisting of: smectite clays, comprising montmorillonite, saponite, beidellite, nontronite, hectorite, stevensite, bentonite; and swellable mica.
 19. The process of claim 18 wherein the lamellar clay has a cation exchange capacity of about 50 to about 200 meq/100 g.
 20. The process of claim 13 wherein the lamellar clay is modified to provide an interlayer distance of said layers of at least 17 Å.
 21. The process of claim 20 wherein the dye solution further comprises an organic onium ion.
 22. The process of claim 21 wherein the organic onium ion is at least one selected from the group consisting of: a primary ammonium ion, a secondary ammonium ion, a tertiary ammonium ion, a quaternary ammonium ion, a pyridinium ion, an imidazolinium ion, a phosphonium ion and a sulphonium ion.
 23. The process of claim 13 wherein the layers delaminated from the lamellar clay are dispersed as individual layers or as groups of less than five layers on average within the dye/clay/polyurethane dispersion.
 24. The process of claim 13 further comprising contacting the fiber with a second dye.
 25. A process for preparing a dyed film comprising a polyurethane, layers delaminated from a lamellar clay, and a dye, said layers and said dye being dispersed in said polyurethane, the process comprising the steps of: (a) contacting a clay dispersion comprising a lamellar clay and a solvent with a dye solution or a dye dispersion comprising an organic dye to form a first dye/clay dispersion; (b) recovering a dyed clay from the first dye/clay dispersion; (c) contacting a solution comprising a polyurethane and an aprotic polar solvent with a second dye/clay dispersion comprising the dyed clay and the aprotic polar solvent to form a dye/clay/polyurethane dispersion; (d) agitating the dye/clay/polyurethane dispersion sufficient to delaminate all or a portion of said layers from the lamellar clay and from each other; and (e) solution casting and drying the dye/clay/polyurethane dispersion to form a dyed film.
 26. The process of claim 1 wherein a dye is also dispersed in said polyurethane dispersion of step (a), the process comprising, before step, (a), the additional steps of: (i) contacting a clay dispersion comprising a lamellar clay and a solvent with a dye solution or a dye dispersion comprising an organic dye to form a first dye/clay dispersion; and (ii) recovering a dyed clay from the first dye/clay dispersion; and then adding said dyed clay to the dispersion of lamellar clay in step (a).
 27. The process of claim 26 wherein the dye is a water-soluble acidic or cationic dye. 